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(No Model.)

B. M. BENTLEY.

ELECTRIC MOTOR.

No. 338,023. 110 Patented Mar. 16, 1886.

vv/ TN E5555 //v l EN TUR UNITED STATES PATENT OFFICEQ,

EDYVARD M. BENTLEY, OF BROOKLYN, NElV YORK.

ELECTRIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 338,023, dated March16, 1886.

Application filed July 10, 1885. Serial No. 171,198. (No model.)

To aZZ whom, it may concern.-

Be it known that I, EDWARD M. BENTLEY, a citizen of the United States,and a resident of Brooklyn, New York, have invented certain new anduseful Improvements in Electric Motors, of which the following is aspecification.

My invention consists in certain devices whereby two or more electricmotors may be run at varying speeds in multiple are on the same circuit.

This invention is especially applicable to electric motors employed forthe propulsion of vehicles upon an electric railway. It is well knownthat when two or more electric motors are in multiple arc with oneanother and run at variable speeds,those motors which run the moreslowly will tend to absorb an undue portion of the current, while thosewhich are running at a greater speed will be deprived of the necessaryamount of current. This tendency is a source of danger to theslow-running motors, since the surplus ofcurrent is apt to be so greatas toinjure or destroy them. I therefore provide a variable resistanceinthe circuit of each motor, and also provide a catch or stop, which willautomatically prevent the removal of too great an amount of resistancefrom the motor-circuit.

In the accompanying drawin M and M represent two electric motors,connected, respectively, to the driving-wheels of two elec triclocomotives. Each motor is provided with a lever, L, for shifting theposition of the comn'iutator-brushes, and also with a lever, L,w hichcontrols an artificial resistance, R, in the motorcircuit. Both thecommutator-brushes and the resistance may be controlled by a singlelever, if desired. Upon each lever L is a toothed sector, A, concentricwith the axis of the lever, and in each motor-circuit is anelectro-magnet, S, whose armature has a pawl, 0. adapted to engage withthe teeth of sector A when the magnetis energized. The magnet S isadapted to respond only to an excess of current beyond a determinedpoint.

The operation of this arrangement is as follows: Suppose that theoperator of the motor has brought it to a standstill by the insertion ofthe resistance R or by the movement of the brushes, or both. Should henow desire to start the motor under a heavy load, or in a situationwhere the motor may be blocked in any accidental manner, he would in theusual manner throw his lever, cutting out the resistance R, and therewould result a sudden flow of current through the motor, which woulddestroy it before it could overcome the inertia of its load or itsblock, were it not for the action of magnet S. The mag net S, becomingenergized when the current reaches a predetermined maximum point, drawsup its armature and interposes the pawl O in the path of any furthermovement of the resistance-lever, so that a driver will be warned thathis current is too great, although he cannot by any degree ofcarelessness or haste permit the motor to be injured.

Various modifications of this device may be employed, the underlyingprinciple of them all being illustrated in the present device, whereinan automatic stop preventstoo great a flow of current through any one ofseveral motors in multiple arc.

\Vhat I claim as my invention is 1. The combination, with an electricmotor, of a resistance in circuit therewith, mechanism controlling saidresistance, and an automatic stop for said mechanism.

2. The combination, with an electric motor, of a resistance in circuittherewith, mechanism controlling said resistance, and an automatic stopfor said mechanism responding to an abnormal increase of currentin themotorcircuit.

3. The combination of two or more electric motors in multiple are on thesame circuit, a resistance in circuit with each mechanism controllingthe same resistances, and automatic stops for said mechanisms.

4. The combination, with two or more electric motors in multiple are, ofa resistance in circuit with each mechanism controlling saidresistances,aud automatic stops for said mechanisms, responding to anabnormal increase of current.

5. The combination,with an electric motor, of a resistance in circuittherewith, mechanism controlling said resistance, and means forautomatically controlling the movement of said mechanism.

In testimony whereof I sign this specification, in the presence of twowitnesses,this the 24th day of June, 1885.

EDXVARD M. BENTLEY.

Witnesses:

ALBERT E. LYNCH, CHAS. H. DORER.

